O.  E.  S.  LIEHART.  GSP,  55,  .   t  '=<°^ 

CONNECTICUT  H  o .  1 R  6 

AGRICOLTORAL  EXPERIMENT  STATION 

NEV/     HAVEN,     CONN. 


BULLETIN   126,  MAY,  1898. 


Insecticides;   Tlieir   Preparation  and  Use, 


CONTENTS. 

Page. 

Notice  as  to  Bulletins  and  Reports 2 

Insecticides  ;  Their  Preparation  and  Use 3 

Materials  used  as  Insecticides 4 

Arsenical  Poisons 4 

Paris  Green 4 

London    Purple 5 

Arsenate  of  Lead 5 

Hellebore 6 

Contact  Poisons -. 6 

Whale-oil "  Soap 6 

Kerosene 6 

Kerosene  and  Water 7 

Kerosene  Emulsion 7 

Fir-Tree  Oil 8 

Tobacco - -.  8 

Pyrelhrum 8 

Poisonous  and  Suffocating  Fumes 8 

Tobacco  Fumes 8 

Hydrocyanic   Gas _  8 

Carbon  Bisulphide _. 9 

Dust 9 

When  to  Apply  Insecticides 9 

Plant  Lice... 10 

Scale  Insects 10 

List  of  Plants,  and  Insects  that  most  commonly  attack  them 10 

Six  Eules  to  be  observed  in  Spraying _ 12 


Notice  as  to  Bulletins. 

The  Bulletins  of  this  Station  are  mailed  free  to  citizens  of  Con- 
necticut who  apply  for  them,  and  to  others  as  far  as  the  limited 
editions  permit. 

Applications  should  be  renewed  annually  before  January  1st. 

The  matter  of  all  the  Bulletins  of  this  Station,  in  so  far  as  it  is 
new  or  of  permanent  value,  will  be  made  part  of  the  Annual 
Report  of  the  Station  Staff. 

All  Bulletins  earlier  than  No.  71  and  Nos.  83,  86,  93,  101,  102 
and  118  are  exhausted  and  cannot  be  supplied. 


Notice  as  to  Supply  of  Station  Reports. 

The  Station  has  no  supply  of  its  Annual  Reports  for  the  years 
1877,  1878,  1879,  1880,  1881,  1882,  1883,  1887  and  1891. 

The  Annual  Report  of  this  Station,  printed  at  State  expense,  is 
by  law  limited  to  an  edition  of  7, COO  copies. 

After  exchanging  with  other  Experiment  Stations  and  Agricul- 
tural Journals,  the  Reports  remaining  at  the  disposal  of  the 
Station  will  be  sent  to  citizens  of  Connecticut  who  shall  seasona- 
bly apply  for  them,  and  to  others  as  long  as  the  supply  lasts. 


Former   Reports  Wanted. 

There  is  frequent  call  for  our  earlier  Annual  Reports  on  the 
part  of  public  Libraries,  students,  chemists,  naturalists,  and  sta- 
tion workers. 

Persons  who  can  supply  copies  of  Reports  of  this  Station  for 
any  of  the  years  above  named,  will  be  likely  to  find  purchasers 
by  communicating  with  the  Director. 


IJ^SECTICIDES :  THEIR  PREPAKATION 

AND  USE. 

By  W.  E.  Britton. 

Bulletin  125  gives  advice  upon  the  methods  of  spraying  plants 
to  prevent  diseases  caused  by  fungi.  The  present  Bulletin 
describes  the  materials  used  to  protect  plants  from  the  attacks 
of  insects,  and  the  methods  of  preparing  and  applying  these 
materials.  Some  of  them  have  been  mentioned  in  Bulletin  121, 
and  in  each  of  our  Annual  Reports  since  1893  may  be  found 
brief  notes  regarding  injurious  insects  and  proposed  remedial 
treatment. 

Spraying  pumps,  suitable  for  applying  insecticides  as  well  as 
fungicides,  are  fully  described  in  Bulletin  125  and  the  reader  is 
referred  to  its  pages  for  information  regarding  them.  A  special 
pump  attachment  for  applying  kerosene,  not  mentioned  in  Bulletin 
125,  is  described  on  page  V  of  the  present  bulletin. 

The  insects  which  are  most  commonly  injurious  to  plants  may 
be  roughly  divided  into  two  classes ;  those  which  eat  and  thus 
destroy  the  vegetable  tissues,  and  those  which  destroy  these  tis- 
sues by  inserting  their  beaks  and  sucking  out  the  plant  juices. 

To  the  former  class  belong  canker  worms,  elm-leaf  beetles,  the 
larvae  of  the  codling  moth,  cut  worms,  potato  beetles  and  tent  cater- 
pillars. To  the  latter  class  belong  the  squash  bugs,  plant  lice  and 
scale  insects. 

Insects  of  the  former  class  are  usually  destroyed  by  spray- 
ing the  leaves  of  the  plants  to  be  protected,  with  some  poison, 
usually  a  preparation  of  arsenic,  which  the  insects  will  unavoid- 
ably eat,  with  the  foliage. 

Insects  of  the  other  class,  namely,  those  which  suck  out  the 
plant  juices,  are  destroyed  by  contact  poisons  or  irritants,  by 
fumes,  or  suffocation.  The  arsenical  poisons,  which  coat  the  leaf 
surfaces,  but  cannot  enter  the  plant  juices,  have  no  effect  whatever 
on  sucking  insects. 

Therefore,  the  method  to  be  used  in  fighting  insect  pests  is 
determined,  first,  by  the  kind  of  insect  to  be  destroyed,  and  then 
by  the  apparatus  at  hand  and  the  convenience  of  the  operator. 


4         CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    126. 

Insects  are  usually  destroyed  by  one  of  three*  distinct  methods 
or  treatments,  viz  : 

(1)  By  internal  poisoning — where  the  insect  devours  portions 
of  plants  that  have  been  coated  with  hellebore,  Paris  green,  or 
any  of  the  arsenical  poisons. 

(2)  Hy  contact  poisons  or  irritants — substances  which  come  in 
direct  extei'nal  contact  with  the  insect  and  which  kill  by  their 
irritating  or  corrosive  action.  Whale-oil  soap,  kerosene,  either 
pure  or  emulsified,  tobacco  decoction  and  hellebore  are  examples. 

(3)  By  poisonous  fumes  and  by  suffocation — where  the  insect 
is  poisoned  or  suffocated  through  the  breathing  pores  by  a  poison- 
ous gas,  or  by  a  fine  powder.  Tobacco  fumes,  hydrocyanic  acid 
gas,  carbon  bisulphide,  benzine  and  fine  dust  of  any  kind  belong 
to  this  class  of  insecticides. 


MATERIALS  USED  AS  INSECTICIDES. 
Arsenical  Poisons. 

Paris  Green,  aceto-arsenite  of  copper,  contains  arsenious  acid, 
copper  and  acetic  acid.  It  is  a  rather  coarse  powder,  bright  green 
in  color,  and  when  mixed  with  water  needs  constant  stirring,  to 
keep  it  in  suspension.  If  not  well  stirred  while  spraying,  the 
poison  will  settle  to  the  bottom  of  the  tank  and,  because  of  its 
concentration,  will  injure  the  foliage,  while  the  liquid  above  it  is 
of  almost  no  value  for  destroying  insects.  Even  when  well  mixed 
with  water  an  application  of  Paris  green  is  likely  to  injure  tender 
foliage.  This  injury  may,  however,  be  prevented  by  adding  lime, 
as  in  the  following  formula  : 

FORMtTLA    FOR    SpRATING     MIXTURE      OF      PARIS     GREEN. 

Paris  green 1  pound; 

Fresh  stone  lime 3  pounds. 

Water. 100  to  200  gallons. 

The  lime  should  be  fresh  and  slaked  just  before  mixing. 

*  Insects  are  sometimes  kept  away  by  the  use  of  substances  known  to  be 
obnoxious  or  distasteful  to  them — as  camphor  is  used  to  keep  off  the  clothes 
moth.  Trapping,  jarring  trees  and  other  mechanical  methods  are  also  occasionally 
used  to  destroy  insects. 


MATERIALS    USED    AS    INSECTICIDES.  5 

When  Bordeaux  Mixture*  is  to  be  apjDlied  to  orchards,  Paris 
green  should  be  added  to  it  in  the  proportion  of  ^  lb.  to  each  45 
or  50  gallons,  thus  making  a  combined  insecticide  and  fungicide. 

The  price  of  Paris  green  is  subject  to  variation,  but  usually  it 
retails  for  about  twenty  cents  per  pound. 

London  Purple. — This  is  a  waste  product  obtained  in  the  manu- 
facture of  aniline  dyes.  Nearly  half  its  weight  may  consist  of 
arsenious  acid,  though  the  percentage  varies  considerably.  In 
some  samples  much  of  the  arsenic  is  in  a  soluble  form,  which  is 
very  likely  to  injure  foliage,  unless  lime  is  added  to  the  mixture* 
This  poison  remains  in  suspension  somewhat  longer  than  Paris 
green.  It  may  be  mixed  with  water  and  lime,  by  the  formula 
already  given  for  Paris  green.  It  costs  from  six  to  fifteen  cents  per 
pound. 

Arsenate  of  Lead. — A  white  powder,  quite  insoluble  in  water, 
and  for  this  reason  less  likely  to  injure  foliage  than  the  other 
arsenical  poisons,  even  when  used  in  excessive  quantity. 

Formula  for  Spraying  Mixture  of  Arsenate  of  Lead. 

Acetate  of  lead 11  ounces. 

Arsenate  of  soda 4      " 

"Water 100  to  200  gallons. 

Dissolve  the  acetate  of  lead  and  the  arsenate  of  soda,  each  by 
itself,  in  a  gallon  or  two  of  warm  water,  and  pour  them  with  con. 
stant  stirring  into  the  rest  of  the  water.  Arsenate  of  lead  forms 
and  is  precipitated  as  a  fine  white  powder,  which  settles  less 
quickly  than  Paris  green. 

*  Bordeaux  Mi.xture  is  prepared  as  follo'ws : 

Sulphate  of  Copper, 5  lbs. 

Lime, -- 5  lbs. 

■Water.- 45  to  50  galls. 

Dissolve  5  lbs.  of  sulphate  of  copper  either  by  adding  it  to  two  or  three  gallons 
of  hot  water  or  by  enclosing  it  in  a  coarse  bag  and  suspending  the  whole  in  a 
half-barrel  of  cold  water  so  that  the  water  just  covers  the  sulphate.  When  dis- 
solved, dilute  with  cold  water  to  15  gallons.  Slake  5  lbs.  of  perfectly  fresh  (not 
air-slaked)  stone  lime  in  a  little  water,  preferably  hot.  When  thoroughly  slaked, 
dilute  and  pour  it  into  the  spraying-cask,  using,  if  necessary,  a  strainer  or  piece 
of  coarse  bagging  to  strain  out  the  coarse  sediment.  If  the  lime  is  of  good 
quality  and  is  properly  slaked,  there  will  be  no  lumps.  Add  water  to  make  30 
galls.  Pour  the  sulphate  solution  as  rapidly  as  possible  into  the  white-wash,  stir- 
ring thoroughly  for  two  or  three  minutes.  The  resulting  mi.xture  should  be  of  a 
pure,  deep  blue  color,  and  should  settle  very  slowly. 

If,  for  any  reason,  it  is  more  convenient  to  reverse  the  process  and  pour  the 
white-wash  into  the  sulphate  solution,  this  may  be  done  with  equallj^  good  results, 
providing  both  solutions  are  dilute. 


6         CONNECTICUT    EXPERIMENT    STATION,   BULLETIN    126. 

Hellebore. 

This  insecticide  is  made  by  grinding  the  dried  roots  of  the 
white  hellebore.  It  is  applied  as  a  powder  or  mixed  with  water. 
Hellebore  is  an  internal  poison  like  the  arsenites,  and  also  appears 
to  poison  some  larvte,  especially  the  currant-worm,  by  contact. 
Against  the  larvae  of  saw-flies  like  the  rose  and  cherry  slugs  and 
the  currant-worm,  hellebore  is  very  efficacious.  It  is  less  poison- 
ous to  man  than  preparations  of  arsenic,  and  therefore  is  to  be 
preferred  for  use  in  the  garden  or  near  the  house.  It  is  however 
distinctly  a  poison,  and  when  it  is  applied  dry,  great  care  should 
be  used  to  avoid  inhaling  the  powder.  It  loses  strength  when 
exposed  to  the  air,  and  a  fresh  supply  should  be  procured  each 
season.     Use  one  ounce  to  two  gallons  of  water. 

Contact  Poisons. 

Whale-oil  soap. — Crude  fish-oil  and  not  whale-oil  is  used  in 
manufacturing  this  article.  It  is  not  uniform  in  composition, 
which  accounts  for  the  variable  results  obtained  by  experimenters. 
Two  soaps  now  upon  the  market,  considered  by  Prof.  Smith*  to 
be  fairly  uniform  in  composition,  are — "  Anchor  Brand  "  made  by 
Leggett  &  Bro.,  301  Pearl  st.,  New  York,  and  the  Good  soap 
made  by  James  Good,  514-518  Hurst  St.,  Philadelphia.  The 
"Anchor  Brand"  soap  sells  for  ten  cents  per  pound,  or  fifteen 
dollars  per  bai'rel  of  about  four  hundred  pounds.  The  Good  soap 
costs  about  four  cents  per  pound  in  bulk.  Strong  solutions  of 
whale-oil  soap  sometimes  thicken  or  solidify  so  that  they  cannot 
be  applied  in  the  form  of  a  spray.  This  is  most  apt  to  happen  if 
,  soda  instead  of  potash  is  used  in  making  the  soap.  Such  solu- 
tions, however,  liquify  when  gently  heated. 

Formula  for  Whale-oil  Soap  Soltttion. 

For  plant-lice  and  other  sucking  insects,  on  a  plant  in  foliage 
use :  one  pound  of  soap  dissolved  in  five  gallons  of  water.  For 
San  Jose  and  other  scale-insects  on  dormant  trees  apply :  two 
pounds  of  soap  in  one  gallon  of  water. 

Kerosene. — This  has  been  used  recently  to  kill  the  San  Jose 
scale.  In  New  Jersey  the  results  have  been  successful,  while  in 
some  other  States  great  injury  has  followed  its  use,  the  fruit  trees 
being  killed  or  seriously  injured.  Kerosene  should  be  applied  in 
the  form  of  a  very  fine  spray  at  a  time  when  the  tree  is  perfectly 
dry  and  when  the  application  will  evaporate  quickly.  It  should 
not  be  used  on  a  damp  or  cloudy  day. 

*  New  Jersey  Rxperimont.  Pfnlion,  Bull.  125. 


MATERIALS    USED    AS    INSECTICIDES.  7 

Kerosene  and  Water. — Kerosene  and  water  can  be  mixed  under 
pressure,  and  a  pump  attachment  is  now  manufactured  expressly 
for  this  purpose.  The  accompanying  figures  show  pail  and  barrel 
pumps  with  kerosene  attachment,  which  is  said  to  deliver  kero- 


sene with  water  in  almost  any  proportion  desired.*  A  mixture 
of  kerosene  and  water  is  much  less  injurious  to  foliage  than  the 
clear  article,  and  kills  many  insects  quite  as  readily. 

Kerosene  Emulsion. — This  has  long  been  the  standard  prepara- 
tion for  destroying  sucking  insects,  and  the  labor  involved  in  its 
preparation  is  perhaps  its  greatest  disadvantage.  It  should  be 
made  as  follows : 


*  This  attachment  is  made  by  the  Demiag  Co.,  Salem,  Ohio,  and  is  also  fitted  to 
their  knapsack  sprayer.  In  each  case  it  can  readily  be  removed.  It  is  stated  to 
have  given  satisfaction  at  the  Cornell  University  station.  The  manufacturer's 
list  prices  for  pumps  with  this  attachment  are  as  follows : — 

Pail  pump ....$10.00 

Knapsack  pump 18.00 

Barrel  pump,  with  iron  air-chamber 26.00 

Barrel  pump,  with  brass  air-chamber 30.00 


8         CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    126. 

Formula  for  Keroskne  Emulsion. 

Kerosene 2    gallons. 

Common  or  whale-oil  soap |  pound. 

Water 1    gallon. 

Dissolve  the  soap  in  the  heated  water  and  while  boiling  hot 
remove  from  the  fire  and  add  the  kerosene.  This  mixture  while 
hot  should  be  driven  with  a  spraying  pump  through  a  coarse  noz- 
zle back  into  the  tub  or  barrel  which  holds  it  until  the  whole  is  a 
creamy  mass  which  thickens  and  becomes  jelly-like  upon  cooling. 
This  may  be  kept  indefinitely,  and  should  be  diluted  for  use  with 
ten  or  fifteen  times  its  volume  of  water. 

Fir-Tree  Oil. — This  is  said  to  contain  the  essential  oil  of  the 
fir.  It  is  soluble  in  water  and  may  be  used  in  the  proportion  of 
one  pint  of  oil  to  five  to  ten  gallons  of  water.  It  is  chiefly  used 
in  greenhouses  to  kill  the  mealy-bug,  and  it  destroys  all  sucking 
insects  as  well.  Cost  alone  precludes  its  more  general  use.  It 
retails  for  seventy-five  cents  per  pint. 

Tobacco. — Tobacco  is  one  of  our  best  contact  poisons,  and  may 
be  prepared  by  steeping  one  jDound  of  tobacco  or  tobacco  stems 
in  two  gallons  of  water. 

Pyretlirum  or  Persian  Insect  Poioder. — This  powder  is  made 
by  grinding  the  flower  heads  and  stems  of  plants  belonging  to  the 
genus  Pyrethrum.  It  is  injurious  to  the  lower  forms  of  animal 
life  but  harmless  to  man  or  the  higher  animals.  It  can  be  used 
in  water  (one  ounce  to  three  gallons)  or  dusted  on  the  plants. 
Used  in  the  former  way,  it  kills  by  contact,  and  in  the  latter  way 
by  sufifocation  as  well.  It  is  also  moistened  and  burned  for  the 
purpose  of  killing  mosquitos,  flies,  and  cock-roaches,  in  dwellings. 

Poisonous  and  Suffocating  Fumes. 

Tobacco  Fumes. — Where  plants  are  confined,  as  in  a  greenhouse 
or  under  a  cloth  tent,  the  fumes  from  slowly  burning,  damp, 
tobacco  stems  kill  sucking  insects.  Too  dense  a  smoke  often 
injures  tender  plants. 

Hydrocyanic  Gas. — To  generate  this  gas,  pour  three  fluid 
ounces  of  water  into  a  shallow  earthenware  vessel,  add  one  fluid 
ounce  of  commercial  sulphuric  acid  and  finally  one  ounce  of 
fused  potassium  cyanide.  This  makes  enough  gas  to  fill  a  space 
of  one  hundred  and  fifty  cubic  feet. 

This  treatment  has  been  used  extensively  in  California  against 
San  Jose  scale,  and  also  in  eastern  nurseries.     A  tight  building 


WHEN   TO   APPLY   INSECTICIDES.  9 

in  which  nursery  stock  can  be  placed,  or  an  oiled  canvas  tent  to 
envelop  the  tree  is  necessary.  Trees  should  be  treated  for  one 
hour. 

Extreme  caution  must  be  taken  in  the  use  of  this  treatment^  as 
the  gas  is  an  exceedingly  dangerous  poison. 

Carbon  Bisulphide  is  used  to  destroy  insects  in  stored  grain. 
One  pound  of  the  liquid  placed  in  shallow  dishes  inside  a  closed 
bin  is  enough  to  kill  the  insects  in  one  hundred  bushels  of  grain 
if  left  for  twenty-four  hours.  This  substance  is  very  inflamma- 
ble and  no  form  of  fire  should  be  brought  near  it.  Its  vapor  is 
also  poisonous  to  animals. 

Dust. 

Many  delicate  larvae  like  rose  slugs  and  cherry  slugs,  may  be 
destroyed  by  blowing  upon  them  any  very  fine  dust  or  powder 
which  has  no  poisonous  properties  whatever,  like  soot,  ashes  or 
fine  dust  from  the  road.  This  fine  material  stops  up  the  breath- 
ing pores  of  the  insect  and  kills  it  by  suffocation.  Finely  ground 
tobacco,  hellebore,  or  pyrethrum  are  often  used  in  this  way,  and 
as  these  substances  are  poisons  as  well,  they  are  more  sure  to  kill 
the  insects  against  which  they  are  used.  For  dusting  plants  sev- 
eral forms  of  powder  guns  have  been  devised  and  put  on  the 

LITTLE 

GIANT 

DUSTER 


Fig.  3. 

market.     Fig.  3  shows  a  form  which  is  manufactured  by  Leggett 
&  Bro.,  301  Pearl  street,  New  York,  and  sells  for  $3.50. 

These  dusters  can  be  used  for  applying  arsenites  or  contact 
poisons  where  these  are  used  in  powder  form. 

WHEN  TO  APPLY  INSECTICIDES. 

Plant  lice  and  scale-insects  may  infest  almost  all  kinds  of  plants. 
All  the  species  do  the  same  kind  of  injuries,  and  with  a  few 
exceptions  all  may  be  destroyed  in  the  same  manner.     For  the 


10      CONNECTICUT   EXPERIMENT   STATION,    BULLETIN    126. 

sake  of  brevity  such  insects  are  mentioned  here  collectively 
instead  of  separately  under  each  host-plant  in  the  following  list. 

Plant-lice. — Plant-lice  are  found  on  tender  shoots  and  leaves  of 
plants,  which  they  damage  or  destroy  by  sucking  the  juices.  On 
fruit  trees  they  usually  infest  the  under  surface  of  the  leaves. 
They  may  be  destroyed  by  spraying  with  whale-oil  soap  solution, 
kerosene  and  water,  kerosene  emulsion,  or  tobacco  decoction 
applied  whenever  the  insects  are  found. 

Scale-insects. — These  fasten  themselves  on  the  bark  of  the  trunk 
and  branches  and  sometimes  upon  the  leaves  and  fruit.  Infested 
trees  should  be  sprayed  with  whale-oil  soap  solution  or  kerosene 
and  water.  The  San  Jose  scale  can  best  be  destroyed  in  winter, 
when  the  trees  are  dormant.  In  winter  clear  kerosene  may  be 
used  against  this  scale,  but  whale-oil  soap  is  a  safer  though  prob- 
ably less  effective  treatment. 

List  of  Plants  and  the  Insects  that  most  Commonly 
Attack  Them.* 

Apple. 

JBud-moth, — Spray  with  arsenicals  (i.  e.  Paris  green,  London 
purple  or  arsenate  of  lead)  in  Bordeaux  mixture  just  before  blos- 
soms appear. 

Canker-worm. — Spray  with  arsenicals  in  Bordeaux  mixture, 
once  just  before  blossom  buds  open,  and  again  as  soon  as  the 
blossoms  have  fallen.  Caterpillars  begin  to  feed  while  leaves  are 
expanding.  Repeat  applications  at  intervals  of  one  week  as  long 
as  necessary. 

Codling-raoth — Apple-curculio — Tent-caterpillar. — Apply  arseni- 
cals in  Bordeaux  mixture  directly  after  the  blossoms  fall,  and 
repeat  at  intervals  of  ten  days  or  two  weeks.  Keep  the  fruit  and 
foliage  well  coated  for  two  months. 

Asparagus. 

Asparagus-Beetle. — Spray  or  dust  plants  with  hellebore  when 
the  cutting  for  market  is  finished  for  the  year.  Spraying  with 
Paris  green  has  been  used  with  success  against  this  beetle. 

*  Only  those  insects  which  can  be  held  in  check  by  the  proper  use  of  insecti- 
cides are  mentioned  in  this  list.  Mechanical  devices,  and  the  insects  combatted 
by  such  means,  are  not  included. 


WHEN    TO   APPLY   INSECTICIDES.  11 

Cabbage. 
Imported    Cabbage    butterfly     or    Cabbage    worm  —  Cabbage 
Plusia. — Spray  or  dust  young  plants  with  hellebore  or  some  form 
of  arsenic.      When   heads   are  forming   use  pyrethrum  instead, 
either  dry  or  mixed  with  water. 

Caerot,  Celery  and  Parsley. 
Celery  Caterpillar. — Dust  with  hellebore  or  pyrethrum.     The 
arsenicals  are  effective,  but  there  is  danger  attending  their  use 
upon  the  parts  of  plants  which  are  intended  for  food. 

Cherry. 
Slug. — Spray  with  arsenicals  in  Bordeaux  mixture,  or  a  solu- 
tion of  whale-oil  soap. 

Gurculio. — See  under  plum. 

Cucumber. 
Striped  Beetle. — Spray  or  dust  with  arsenicals  whenever  the 
beetle  appears. 

Currant  and  Gooseberry. 
Imp>orted    Currant-worm. — Spray   with    hellebore   as   soon   as 
leaves   unfold,   or   dust   it   on   the   plants    whenever   the   larvae 
appear.* 

Grape. 

Grape-slug  or  Sawfly. — This  insect  is  easily  destroyed  by  the 
use  of  the  ar8enical«,  hellebore,  or  the  contact  poisons. 

Flea-Beetle. — Spray  with  arsenicals  when  the  buds  are  first 
attacked  by  the  adults,  and  again  when  larvae  appear. 

Peach. 
Carculio. — See  under  plum. 

Pear. 

Codling-Moth. — See  under  apple. 

Slug. — Use  arsenicals  in  Bordeaux  mixture,  same  as  for  the 
cherry  slug. 

Psylla. — Spray  thoroughly  with  kerosene  emulsion  when  the 
leaves  are  first  expanding.  The  insects  are  then  young,  and  not 
enveloped  in  honey-dew.  If  later  applications  are  necessary  they 
should  be  made  just  after  a  rain. 

*  Dry  hellebore  is  poisonous  when  inhaled  and  the  operator  should  handle  it 
with  care. 


12      CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    126. 

Plum. 

Curculio. — Arsenicals  in  Bordeaux  mixture  should  be  applied 
once  before  blossoms  open,  and  again  just  after  they  have  fallen.* 
Canker- worm. — See  under  apple. 

Potato. 

Colorado  Beetle. — Spray  with  arsenicals  in  Bordeaux  mixture 
when  the  beetles  first  appear  and  repeat  as  often  as  necessary. 
The  arsenicals  mjty  also  be  dusted  upon  the  plants. 

Rose. 

Slug. — Dust  with  any  fine  powder,  or  spray  with  hellebore  or 
the  arsenicals. 

Leaf  hopper. — Spray  the  under  surface  of  the  leaves  with  whale- 
oil  soap  solution  or  kerosene  emulsion.  When  plants  are  wet 
dust  freely  with  pyrethrum  or  ground  tobacco. 

Squash  and  Pumpkin. 

Striped  Beetle. — See  cucumber. 

Squash  Bxig. — Spray  the  young  bugs  with  kerosene  emulsion  : 
duet  with  pyrethrum. 

SIX  RULES  TO  BE  OBSEKYED  IN  SPRAriNG. 

1.  Never  spray  fruit  trees  when  in  bloom,  for  bees  are  killed 
thereby.     Bees  are  needed  to  pollinate  the  blossoms. 

2.  Always  begin  the  treatment  early.  If  the  foliage  has  been 
destroyed  there  is  little  use  in  spraying  the  tree. 

3.  Use  care  in  handling  the  poisons.  Do  not  store  them  where 
children  or  animals  can  get  at  them. 

4.  When  possible  spray  when  there  is  promise  of  fair  weather. 
Never  spray  when  a  storm  is  beginning. 

5.  Perform  the  work  thoroughly.  Be  sure  and  cover  every 
portion  of  the  plant  with  the  liquid. 

6.  It  is  advantageous  to  apply  Paris  green  and  Bordeaux  mix- 
ture together  when  admissible.  Injuries  resulting  from  the 
attacks  of  both  insects  and  fungi  will  thus  be  forestalled. 

*  Many  persons  fight  this  pest  entirely  by  jarring  the  trees  each  morning  and 
destroying  the  beetles  which  are  collected. 


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